Numerous surgical procedures have been developed to replace arteries that have become blocked by disease. For example, in coronary bypass surgery, a vein may be harvested from elsewhere in the body and grafted into place between the aorta and the coronary artery. It is generally preferred to use a vein taken from the patient undergoing the surgery, as the patient is a ready source of suitable veins that will not be rejected by the body after grafting. In particular, the saphenous vein in the leg is often used for this procedure. The saphenous vein is typically 3-mm in diameter, comparable in size to the coronary arteries. Furthermore, the venous system of the legs is sufficiently redundant that the saphenous vein may be removed and the remaining veins in the leg will continue to provide adequate return blood flow. Alternatively, the cephalic vein in the arm may sometimes be used as well.
Traditionally, to harvest the saphenous vein, an open surgical procedure has been used to expose and remove the vein from the leg. A series of incisions with skin bridges (and sometimes a long single incision) is made from the groin to the knee or to the ankle. Once the vein is exposed, the surgeon dissects the vein from the surrounding tissues, lifts the vein from the tissues, and divides and ligates the various tributary veins that feed into the saphenous vein. Once the vein is completely mobilized, the surgeon cuts the ends of the vein and removes it from the leg. The long incisions in the leg are closed, and the vein is prepared for implantation.
More recently, vein harvesting has been accomplished using endoscopic procedures. One or more small incisions are made at selected target sites for providing access to the vein being harvested. For example, to harvest the saphenous vein, an incision may be made at the groin, at the knee, and/or at the ankle. A tunneling instrument, such as a blunt or soft-tipped dissector may be utilized to dissect a subcutaneous space along the anterior surface of the vein being harvested. Such instruments generally include a substantially transparent elongate member having a rounded distal end and a passage therein for receiving an endoscope, the endoscope providing visualization through the end and/or side walls of the dissector. The tunneling instrument is inserted into the incision and advanced or pushed along between tissue layers to identify the saphenous vein. The tip of the dissector is generally kept in contact with the vein and the dissector is advanced along the tissues, thereby creating a small tunnel along the anterior surface of the vein. An inflatable balloon may then be introduced into the tunnel (or alternatively provided in a collapsed condition on the tunneling instrument prior to insertion into the incision), and inflated to enlarge and further propagate the tunnel. The balloon may be used to dissect fat and skin overlying the vein and to enlarge the tunnel to an appropriate size.
Once the desired length of vein is exposed and an appropriate tunnel developed, the balloon and/or dissector is removed, and a retractor, typically a wide flat shaft with a handle on its proximal end, is prepared. The retractor is inserted into the incision and directed along the dissected path over the section of vein to be harvested. The handle of the retractor may then be lifted away from the surface of the leg, creating a space under the shaft adjacent the vein.
Surgical instruments, such as a vein harvesting hook, may then be inserted into the space to strip away tissues surrounding the vein, ligate tributary veins, and mobilize the vein. Typically, the retractor has substantially transparent walls and an endoscope is provided in a passage in the retractor, thereby allowing visualization during the harvesting procedure.
Conventional retraction devices, such as those used in the vein harvesting procedure just described, often have limitations. For example, such retractors typically require external support to hold the retractor away from the surface of the vein and maintain the anatomic space. The surgeon may have to hold the handle on the retractor, preventing both hands from being free for the procedure or requiring an assistant. Alternatively, an external mechanical support may be provided to hold the retractor, but such a support may interfere with access to the operative site.
Some retractors include a distal hood capable of maintaining a space thereunder. These hoods, however, only create a limited self-supported space, requiring that the retractor be moved when it is desired to work in a new location. Such retractors also generally require external support to provide a space along the retractor shaft between the incision and the hooded space.
In addition, some retractors include a channel to direct an endoscope to the operative site. An endoscope inserted into such a conventional retractor, however, may not allow the surgeon to monitor the surgery as effectively as desired. For example, the walls of the retractor may cause glare or distortion impairing visualization of the vein. Further, although the endoscope may be moved axially within the channel in the retractor to view the section of vein, lateral movement may be limited without also moving the retractor itself. The proximal end of the endoscope may also partially obstruct the incision, and may impair introduction of surgical instruments into the anatomic space.
Accordingly, there is a need for a self-supporting retractor capable of holding open an anatomic space for endoscopic vascular procedures that does not require external support to maintain the space.
In addition, there is a need for a retractor for holding open an anatomic space for endoscopic procedures that provides improved visualization within the space.